The present invention relates to a discharge-lamp lighting device used as headlights of a vehicle and the like.
With conventional discharge lamps (FIG. 12) used as headlights of a vehicle, lamp sockets 1 are provided in respective lamp-mounting places of the vehicle and lamp-lighting devices 15 each containing a high-voltage generating transformer with a control circuit assembled on a printed circuit board are separately mounted in a bonnet of the vehicle. The lamp-lighting lighting devices 15 are connected to the respective lamp sockets by using separate high-voltage cables 16 and low-voltage cables 17.
Japanese Laid-open Patent Publication No. 8-130127 discloses a compact discharge-lamp lighting device constructed as follows:
A coil case has a primary coil formed by plural plate conductors (insertions) molded thereon and contains therein a secondary-coil wound bobbin with a core inserted in a hollow center thereof and potted therein with insulating resin to form a solid coil case unit. The coil case unit is then mounted on a printed circuit board having a circuit component pattern to finish a discharge lamp lighting circuit. The printed circuit board is further provided with a shield portion for protecting the circuit elements against the possible effects of the high-voltage generating portion in the coil case unit.
As described above, the conventional discharge lamp lighting device requires separate arrangement of a lamp socket apart from the lamp lighting circuit unit and interconnection of them by using a high-voltage cable. This complicates the mounting work of the lighting device.
Furthermore, the use of elongated high-voltage cable may be associated with the risk of a leak current therefrom and reduction of the output voltage of the discharge lamp lighting device.